NEC PD754144 - Manual (Page 182)

CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
182 User’s Manual U10676EJ3V0UM
0.5
16
15.5
16
6.5.2 Programmable threshold port mode (PTHM) register
PTHM is an 8-bit register that controls the programmable threshold port operation, and it is set by an 8-bit
memory manipulation instruction.
The threshold voltage can be selected by specifying the lower four bits of PTHM within 16 steps as follows.
AV
REF
× - AV
REF
×
It is also possible to reduce the current consumption if the comparator operation is stopped (PTHM7 = 0). All
bits of PTHM are initialized to “0” by RESET signal generation, and the operation stop mode is entered.
Cautions 1. Bit 4 and 5 of PTHM must be set to “0”.
2. If a STOP or HALT instruction is executed during comparator operation (PTHM7 = 1), the
operation stop. Therefore, a PTH0 read manipulation must be executed after the standby
mode is released, input voltage is applied to the PTH00 and PTH01, and the conversion
time has elapsed.
3. The conversion result of the programmable threshold port becomes undefined when the
operation is stopped. Read the conversion result during comparator operation.
Figure 6-50. Format of Programmable Threshold Port Mode (PTHM) Register
Comparator operation mode specification
PTHM7 Operation mode
0 Comparator operation stopped
1 Comparator operating
Conversion time (maximum) selection Note
PTHM6 Conversion time
0 17 × 32/f
X
(130 µs)
1 17 × 8/f
X (32.4 µs)
Values in parentheses are applicable when f X = 4.19 MHz
in the µPD754244.
Threshold voltage selection
Values set to PTHM3-PTHM0 Threshold voltage (V
REF
)
n
(0 ≤ n ≤ 15)
AV REF
×
Note “PTHM6 = 1” can only be set when PCC = 0010B or 0011B.
7 6 5 4 3 2 1 0
PTHM7 PTHM6 0 0 PTHM3 PTHM2 PTHM1 PTHM0 FD6H
Address
PTHM
Symbol
(n + 0.5)
16